In the synthesis of 4"-amino avermectin derivatives, the introduction of the amino group through a reductive amination of the 4"-oxo intermediate, using traditional imine formation and reduction techniques such as ammonia or methylamine and NaBH.sub.3 CN was achieved in poor yields of between 20 and 65%. These poor yields were due to incomplete imine formation, base-induced epimerization at the 2-position and cyanoamino formation. The instant process is a significant improvement over other prior processes achieving yields of about 85-90% for the reductive amination. The compounds produced by the novel process of this invention and the prior processes for their preparation are known in U.S. Pat. Nos. 4,427,663 and 4,874,749.